Influence of Baseline HbA1c and Antiplatelet Therapy on 1-Year Vein Graft Outcome

The influence of baseline HbA1c levels on vein graft outcomes post coronary artery bypass grafting (CABG) remains unclear. The purpose of this study was to assess the association between baseline HbA1c and 1-year vein graft patency, and the effects of antiplatelet therapy on the 1-year vein graft patency after CABG in patients with baseline HbA1c <6.5% vs ≥6.5%. We examined the subgroups with baseline HbA1c <6.5% vs ≥6.5% from the DACAB trial (NCT02201771), in which 500 patients were randomly allocated to receive ticagrelor plus aspirin (T+A), ticagrelor alone (T), or aspirin alone (A) for 1 year after CABG. The primary outcome was the vein graft patency (FitzGibbon grade A) at 1 year. A total of 405 patients with available baseline HbA1c data were included in this subgroup analysis. Of them, there were 233 patients (678 vein grafts) with baseline HbA1c <6.5% and 172 patients (512 vein grafts) with baseline HbA1c ≥6.5%. Compared with the HbA1c <6.5% subgroup, the HbA1c ≥6.5% subgroup showed worse 1-year vein graft patency (adjusted odds ratio [OR] for nonpatency: 1.69, 95% confidence interval [CI]: 1.08-2.64). T+A showed higher vein graft patency than A in both HbA1c <6.5% (adjusted OR for nonpatency: 0.34, 95% CI: 0.15-0.75) and HbA1c ≥6.5% subgroups (adjusted OR for nonpatency: 0.45, 95% CI: 0.19-1.09), without an interaction effect (P for interaction = 0.335), whereas T did not show more significant improvement than A in both subgroups. In the DACAB trial, lower baseline HbA1c was associated with higher vein graft patency 1 year after CABG. T+A improved 1-year vein graft patency vs A, irrespective of baseline HbA1c.